*Expanded math error authority was implemented in calendar
year 1997 for tax year 1996; data prior to FY 1998 does not include earned
income tax credit (EITC) or taxpayer identification number (TIN)
"math errors."
Return counts are for prior calendar year.
**Spike caused by taxpayer confusion with the advance payment of the rate reduction credit.
***Basis for counts revised between 2003 and 2004 to exclude prior year returns. If 2003 had been reported using same definition, would have been 4,024,981. Spike in 2004 largely due to large jump in child care credit math errors.
Figures for 2005 and 2006 now count notices rater than math errors since a single return may have more than one error. If rate had been based on math errors in 2006, it would have been 3.1, instead of 2.4.
****Basis of counts changed from number of contacts to cases closed in 2004 and later years.